Much time and expense has been invested in technologies that secure content against unauthorized distribution and use, especially with regards to global-scale media distribution systems supporting ˜trillions of individual content copies and ˜billions of rendering devices. These prior art technologies commonly involve encrypting the content, so that only users licensed to access the content can do so.
Although many of these protection technologies are sophisticated, they suffer from a fundamental flaw: the content cannot be secured always. To have any value, it must eventually be rendered for presentation to a human consumer (e.g., displayed on a screen for viewing; converted into sound for listening, etc.). When the content is rendered, it can be electronically re-captured (e.g., using a microphone, or more generally, digitally capturing uncompressed/unencrypted signals as they journey toward speakers or display screens, or to the user). The person who re-captures the content can then re-distribute it. Thus, perfect protection is unattainable.
(There are very limited cases where re-capturing may be prevented, e.g., in controllable rendering environments, such as cinema auditoriums or high security briefing rooms. And there are a variety of cases in which re-capturing is not objected-to, or may be desired. These are not the focus of the present work.)
Once a person has re-captured content, there are myriad options for its re-distribution. Free distribution, e.g., on peer-to-peer networks or bulletin board/warez download sites, is one possibility. Another is for the pirate to commercially re-distribute the content—using protection techniques of the sort that were initially applied to the content, e.g., encryption and/or sophisticated digital rights management technologies. This presents the ironic dilemma of advances in protection technologies being turned against lawful copyright proprietors.
Of course, the pirate may simply keep the re-captured content for his own subsequent use.
Given the ultimate futility of content protection, the best that may be done—at a most fundamental level—is to have the rendered content convey a substantially unerasable identity, e.g., using a digital watermark. Better still, it would be ideal if this identity could somehow be integral in the initial rendering of the content in the first place, as well as becoming an economically debilitating impediment to any pirate attempting to utilize legitimate global-scale distribution systems for redistributing the otherwise copy-able content.
Although different types of watermarks can be employed for this identification purpose, one attractive option is to use asymmetrical digital watermarks. These are marks from which a decoder can extract information, without knowledge of how the content was originally encoded. Such marks are appealing because the absence of knowledge about encoding prevents calculated attacks seeking to precisely counteract the mark. Instead, attacks on such marks are generally limited to trying to drown out the watermark signal, e.g., by applying high levels of noise, distortion or such general mischief. These types of attacks inevitably impair the quality of the underlying content, comprising its commercial value. The beauty behind the general notion of asymmetrical digital watermarking is that such attacks never truly erase the watermark, they merely attempt to interfere in some particular instance or class of identification procedure.
Herein lies a fundamental flaw in such “functional erasure” attacks, in that they are not future-proof. Said another way, time is on the side of engineers who can design better and better methods of detecting traces of residual asymmetric watermarks, as opposed to copyright-pirates who attempt to erase traces of such watermarks under the constraint of not thoroughly degrading the value of the copied content.
While identification marking of content is a useful component of a layered security system, it will not—alone—prevent a pirate from profiting from his piracy. To do this, the watermark should also play a role (or multiple roles) in consumption of the content.
In accordance with one particular embodiment of the present invention, electronic content is encoded with a watermark associating it with a particular consumer. When presented for playback, the rendering equipment examines the watermark to confirm that the consumer with whom the content is associated, is also the consumer with whom the equipment is associated. If there is no watermark—or if the watermark is associated with a different consumer, then playback is refused.
The equipment also desirably checks the content for tell-tale signs of piracy. In one arrangement, the equipment checks to see if the content has a second watermark (or even a very feeble remnant thereof), indicating that the content has been derived from content earlier provided to a different consumer. If such a check proves positive, playback is again refused. (As considered below, a pirate's attempt to conceal or remove this earlier watermark is unlikely to succeed.)
Thus, this illustrative rendering equipment will refuse to play if there is no watermark; if there is one watermark not associated with the proprietor of the equipment; or if there are two or more watermarks.
It will be recognized that the foregoing arrangement addresses the problem of content re-capture and re-distribution. If content is re-captured from user A and re-distributed to user B, user B's rendering device(s) will refuse to play. Either the re-Distributor will not have added a watermark associating the content with user B—leading the rendering device to discover that such content is not intended for user B; or the re-Distributor will have added such a watermark—and the rendering device will refuse playback because it finds two watermarks. (Certain embodiments of the invention permit a legitimate purchaser to physically bring their copy of content to a friend's house and play it there; it is only when a copy of the content is transferred to the friend's system without involvement of the copy's intended proprietor that playback is foiled.)
As a pragmatic matter, consumers, content producers and infrastructure vendors will not gravitate toward adopting a new media distribution system simply because it eliminates mass-scale piracy; a new media system must fundamentally provide new benefits to all three constituencies in the media marketplace. Arrangements detailed herein provide benefits for each constituent and all three as a group, thereby addressing the otherwise daunting problem of non-compliant legacy media players and “rogue players.” Both of these latter apparent piracy avenues can be rendered economically unattractive to pirates and the media consumers alike, and thus relegate both to the same fringes of consumers and providers that typified the 1970s-era bootleg tape culture.
The foregoing is just one of many forms of the invention, and is subject to numerous novel variations. Other arrangements are disclosed in the detailed description, which proceeds with reference to the accompanying drawings.